1. Field of the Invention
The present invention relates to an interface circuit, and more particularly to an interface circuit for performing data transfer between a host device (such as personal computers and printers) and a peripheral device (such as memory cards). In addition, the present invention also relates to a system device using the interface circuit and a data interface method.
2. Discussion of the Background
In recent years, memory cards including a flash memory is used as data storage and transmission devices for digital equipments such as portable phones, digital cameras, personal computers and printers.
Specific examples of such memory cards include PC CARD (trademark) and COMPACT FLASHCARD (CF CARD) (trademark). With respect to CF CARD, which is smaller in size than PC CARD, the below-mentioned PC CARD adaptors have been developed and commercialized so that CF CARD can be used for system devices having a PC CARD slot.
Specific examples of the data transfer mode for CF CARD include three modes, i.e., a memory mode, an I/O mode and a True IDE mode at the present time. Among these modes, the True IDE mode has been used for high-access-speed transmission because Card Bus has been developed and commercialized. Thus, it is possible for the True IDE mode to perform data transfer at a higher speed than in the case of using other modes.
An example of conventional systems including a PC CARD interface using CF CARD will be explained by reference to FIG. 1. FIG. 1 is a block diagram illustrating a background system device including a PC CARD interface.
Referring to FIG. 1, a CF CARD 16 is inserted into a 16-bit PC CARD adaptor card 14, and the 16-bit PC CARD adaptor card 14 is attached to a PC CARD connector 10 provided on the background system.
The PC CARD connector 10 is provided on a PC CARD controller 2′ in the conventional system. The PC CARD controller 2′ communicates with a host device 12, which is a main device of the system, via a PCI bus 30 to transmit and receive data to or from the host device 12.
When the 16-bit PC CARD adaptor card 14, into which the CF CARD 16 has been inserted, is attached to the PC CARD connector 10, the PC CARD controller 2′ recognizes that a 16-bit PC CARD 16 has been attached, and transmits the information (i.e., attachment of a 16-bit PC CARD 16) to the host device 12. Hereinafter, the host device 12 accesses the PC CARD controller 2′ using a 16-bit PC CARD transfer mode (i.e., a 16-bit PC CARD ATA mode).
In this regard, the 16-bit PC CARD ATA mode is compatible with a memory mode and an I/O mode of CF CARD. Therefore, the PC CARD controller 2′ can transmit and receive data to or from CF CARD without using an interface circuit. Therefore, data transfer between the host device 12 and CF CARD 16 which is inserted into the 16-bit PC CARD adaptor card 14 is performed via the PCI bus 30, a PCI interface block 8′ and a 16-bit card interface block 4 as illustrated by a dotted line in FIG. 1.
The memory mode and I/O mode of CF CARDs is called a PC CARD ATA mode. The data transfer between a CF CARD and a system device is one of most popular data transfer.
However, as mentioned above, there are some CF CARDs having a True IDE mode capable of performing high speed data transfer. Specifically, almost all CF CARDs, which have been developed and commercialized recently, have a True IDE mode. However, when a card having a True IDE mode is used for the conventional system illustrated in FIG. 1, a problem which occurs is that only the data transfer in a PC CARD ATA mode can be available, namely, high speed data transfer cannot be performed.
Another example of conventional systems including a PC CARD interface using CF CARD will be explained by reference to FIG. 2. FIG. 2 is a block diagram illustrating another background system device including a PC CARD interface. The system device illustrated in FIG. 2 has a Card Bus card adaptor card 14′ is used instead of the 16-bit PC CARD adaptor card 14.
Referring to FIG. 2, the CF CARD 16 is inserted into the Card Bus card adaptor 14′ and the Card Bus card adaptor 14′ is attached to the PC CARD connector 10 provided on the system device. In this case, the PC CARD controller 2′ recognizes that a Card Bus card is attached, and transmits the information (i.e., attachment of a Card bus card) to the host device 12. Hereinafter, the host device 12 accesses the PC CARD controller 2′ using a Card Bus card transfer mode.
In this regard, the Card Bus card transfer mode is not compatible with any of the transfer modes of CF CARD. Therefore, it is necessary to convert the signal to a signal which can be used for any one of the CF CARD transfer modes. The background Card Bus card type adaptor card 14′ illustrated in FIG. 2 includes an IDE interface block 18 therein to use a high speed transfer mode, i.e., the True IDE mode. Therefore, the CF CARD 16 performs data transfer using the True IDE mode.
Therefore, data transfer between the host device 12 and the CF CARD 16 which is inserted into the Card Bus card adaptor card 14′ is performed via the PCI bus 30, the PCI interface block 8′ and a Card Bus card interface block 6 as illustrated by a dotted line in FIG. 2.
However, all of existing CF CARDs are not compatible with the True IDE mode. For example, CF CARD-shaped modem cards which are used as modems are compatible with only the I/O mode. When such a card is inserted into the Card Bus card adaptor card 14′ data transfer between a system device and the card (i.e., modem card) cannot be performed.
Published unexamined Japanese patent application No. 2005-157760 discloses an information processing device, a PC CARD control circuit and a control method concerning control of mode of PC CARD. In the publication, the mode is controlled by a CPU.
Because of these reasons, a need exists for a technique such that a CF CARD compatible with the True IDE mode is operated using the True IDE mode while a CF CARD not compatible with the True IDE mode is operated in the PC CARD ATA mode in data transfer between a system device including a PC CARD controller and a PC CARD connector, and a CF CARD inserted into a PC CARD type adaptor.